Study On Condition-based Cold Running-in System Of Engine

Engine is the power core of automobile, and its performance will affect the performance and service life of automobile directly. But for engine with major repairs, running-in is the main way to increase its repair quality, performance and service life. Cold running-in is the major component of running-in, so the correct and reasonable cold running-in will affect the performance and service life of engine with major repair. At present, the running-in standard, "speed at level and timing", is generally used in repair field, that is making cold running-in for engine with fixed speed and time according to running-in criterion of the new engine supplied by the engine factory. The quality of engine with major repair is different because of applying different quality parts, the level of the repair, processing and repair technique. So it is difficult to insure the quality of running-in for the engine with different repair quality applying the same running-in standard, for example, for the engine with poor repair quality could not meet running-in standard, for the engine with good repair quality which could meet the standard, but the service life is affected because of too long running-time. Cold running-in standard like Oil Analysis Technology can make the engine get perfece running-in performance, but it is hard to make it popular because of complicated operation and the requirement is too high for the operator. At the same time, the engine of different type must have the special fixed-support equipment in running-in process, but it is difficult for repair shop to produce or buy fixed-support equipments for every type engine, and workload of changing fixed-support equipment in running-in process, all these factors limit the spread of cold running-in in repair industry and influence the repair quality and usage performance. To sum up, the existing cold running-in standard and test bench can't insure the running-in quality of the major repair engine, and restrict to spread of cold running-in in repair industry and influence the usage performance and service life of engine.Based on background mentioned above, this paper is about study the cold running-in technology of engine. The paper puts forward condition-based cold running-in criterion of engine through studying some influences on cold running-in of engine and the change of cylinder compression pressure and anti-drag torque in cold running-in of engine. The paper designs the condition-based cold running-in system of engine according to the condition-based cold running-in criterion of engine. The main contents of the study and the results are as follows:1. The paper analyzes the drawbacks of exiting cold running-in bench and criterion. The shortcoming exiting cold running-in bench can't fix and support every type engine which is put forward through studying the running-in bench applying. A lot of problems exiting in cold running-in criterion can't achieve the optimized cold running-in standard which is put forward through studying the exiting cold running-in criterion, and it causes that some engine can't achieve running-in quality after running-in, some reduce the service life for too long running-in time, and some cold running-in criterion can achieve the optimized cold running-in standard, but it is difficult to spread in repair trade for some reasons.2. The paper puts forward cold running-in criterion of engine. The constitute way of running-in loading and running-in speed that can improve the efficiency of cold tunning-in is drawn up though studying the factors that influence cold running-in of engine; the constitute theory of running-in time puts forward though studying the change of cylinder compression pressure and anti-drag torque in cold running-in process of engine. The condition-based cold running-in criterion puts forward based on load, running-in speed and running-in time that made according to above ways and theory.3. The paper designs and exploits the condition-based cold running-in system of engine. The condition-based cold running-in system of engine is designed and exploited based on the condition-based cold running-in criterion of engine, the system includes condition-based cold running-in test bench, the support system of condition-based cold running-in, the collection and input conversion of signal and output control system and the software of control system. The condition-based cold running-in test bench of engine includes the ground foundation, the anti-drag system and the fixed-support bench. The ground foundation is designed according to system requirement and the actual situation of the place, it includes water cooling cycle system and the foundation of bench. The anti-drag system can drag a variety of types engine in scope of a certain power, and connected easily, it reduces the workload of bench connection greatly. The fixed-support bench can be installed and fixed a variety of models of engine that have different fixed-support way, and it can expand the system using range. The support system of condition-based cold running-in features with ensureing cold running-in process of a variety of models engine safely, its high control accuracy, low cost, simple and practical which makes it spread in repair trade easily. The software of control system can analyze the collecting data, adjust and control running-in process according to the results of the analysis, realize condition-based cold running-in of engine, operate easily, get high automation and don't need operater with high knowledge which makes it spread in repair trade easily.4. The condition-based cold running-in criterion of one style engine is constituted according to its test data, and condition-based cold running-in system of engine is applied in running-in Practice, and the test results is analyzed. The analysis results show that the cold running-in criterion of engine that constituted based on test data can running engine appropriately according to its repair quality, and it reduces running-in time in ensuring the quality of the premise of running-in and achieves the optimized running-in standard. Condition-based cold running-in system can be fixed and connected easily, and the application range is wide, and which can reduce workload and work intensity. The main innovations of the study are as follows:1. The condition-based cold running-in criterion of engine is put forward first. The constitute way of running-in loading and running-in speed that can improve the efficiency of cold tunning-in is drawn up though studying the factors that influence cold running-in of engine; the constitute theory of running-in time is put forward though studying the change of cylinder compression pressure and anti-drag torque in cold running-in process of engine. The condition-based cold running-in criterion is put forward based on load, running-in speed and running-in time that made according to above ways and theory.2. The condition-based cold running-in system of engine is designed and exploited. The condition-based cold running-in system of engine is designed and exploited based on the condition-based cold running-in criterion of engine, the system can be fixed and connected easily, meet a variety of models of engine, make application range wide, reduce workload and work intensity. The software of control system features with high automation, the control system can be operated easily, and the running-in time can be adjusted according to the repair quality of engine, realize condition-based cold running-in of engine which ensure the running-in quality and improve the running-in efficiency.The studies on cold running-in technology of engine is few at home and abroad, the paper design the condition-based cold running-in system of engine, it is great significance to improve the usage performance and prolong service life and the cold running-in of engine spread and develop in repair field.